1. The Field of the Invention
This invention relates to apparatus used to determine the response of a human patient to tactile stimulation. More particularly, the present invention relates to systems and methods for quantifiably determining a patient's responses to a variety of tactile stimuli in a repeatable and reproducible manner.
2. The Prior Art
Many medical professionals and researchers need to determine a patient's response to various modes of tactile stimulus. For example, medical professionals dealing with the human nervous system often need to determine a patient's response to various tactile stimuli to assess the extent of any damage to the nervous system due to trauma or a degenerative condition.
Still further, rehabilitation and physical therapists concerned with monitoring a patient's progress during recovery from a head injury, stroke, or some other event affecting somatosensory function also must conduct tactile testing. Moreover, primary care providers often desire to perform tactile testing as a routine screening procedure for their patients but have been unable to do so because of the specialized training and experience needed to perform tactile testing using existing methods.
It is now common for standard diagnostic tests to be used by neurologists, neurosurgeons, plastic and hand surgeons, and other surgeons to assess the functioning of a patient's nervous system. For example, in cases of central pathway lesion, differential loss of high versus low frequency vibration sense, temperature, and pain sensitivity is diagnostic of the pathways involved.
It is generally necessary to test all three of the principal modalities of cutaneous sensation, i.e., temperature, pain, and touch, in order to completely assess a patient's condition. Prior art methods of testing the patient's thresholds and suprathresholds of temperature, pain, and touch involve manually applying the stimulus to the patient. Such prior art manual methods are time consuming to prepare or administer, require a subjective determination by the administering technician, and are not consistently applied or reproducible from test to test.
For example, in order to test for pain using prior art methods, a technician commonly jabs the patient with a sharp needle until a response is obtained. The manual jabbing of the patient with a needle requires that the technician be experienced at jabbing patients in order to avoid inflicting too much pain and drawing unnecessary blood. Still, regardless of the experience of the technician the use of the prior art jabbing method does not result in quantifiable, objective, and reproducible results.
In the case of testing a patient's response to different temperatures, the prior art methods include having the patient touch vials or test tubes filled with liquids heated to varying temperatures. Aside from the difficulty of filling, heating, and maintaining the temperature of the vials or test tubes, the prior art method is not well suited to testing the patient's tactile response to elevated temperatures on all areas of the body.
When measuring the patient's response to touch and vibration the prior art methods use various apparatus. Such apparatus include horse hairs and monofilament lines of varying thickness and stiffness which a technician presses against the patient's skin. Tuning forks are used to determine the patient's tactile threshold of sensing vibration.
In addition to the clinical application of tactile testing, neuroscience researchers interested in testing somatosensory function in man and other mammals routinely carry out tactile testing as part of their work.
In view of the foregoing, it would be an advance in the art to provide a system and method to accurately and reproducibly test a patient's responses to one or more tactile stimuli. It would also be an advance in the art to provide response to various modes of tactile stimulation which does not require special expertise to operate and maintain a record of the results of the testing. It would be a further advance in the art to provide a system and method for automatically testing the tactile responses of a patient which imposes quantifiably accurate stimuli upon command and which carries out the testing in a relatively short period of time.